DOWN IN New Orleans they’re having Mardi Gras, and I don’t know whether the rest of us are supposed to laugh or cry.

Let’s see, vast tracts of the city are mold-infested and uninhabited, some neighborhoods are reduced to rubble, two-thirds of the population is dispersed around the country, more than a thousand people are dead, the levees around the city are patched together, in just three months or so a new hurricane season begins — and the people of New Orleans are spending precious time and energy to throw a humongous party in the streets.

Last fall, even before the devastating floodwaters had receded, the shape of this year’s post-tragedy Mardi Gras had become a matter of serious public debate, the stuff of impassioned letters-to-the-editor.

Anyone who dared suggest that maybe the city ought to think about skipping the party, just this once, was peremptorily dismissed — not just the know-nothing outsiders (like me) who couldn’t possibly understand, but the displaced evacuees sitting in cramped apartments outside Houston or Dallas, stunned that their hometown would stage a Mardi Gras that so many of its people couldn’t possibly come home to enjoy.

I found this show-must-go-on consensus jarring, but I should have thought back to my time as a correspondent for The Washington Post covering South America, specifically Brazil, and remembered just how important the tradition of pre-Lenten carnival can be to a society.

Carnival in Brazil is more than an officially sanctioned bacchanal, it’s more like a national birthright — a guaranteed, weeklong interlude when lots of inhibiting rules are suspended, most societal barriers are ignored and all manner of oppressive problems are deferred.

Of course, putting problems out of your mind doesn’t make them go away. It was while I was, ahem, “covering” carnival in Rio one year that I was able to see in starkest relief the racial and economic disparities in Brazilian society.

There could have been no carnival without the multitudes of poor, black Brazilians who dressed up in fabulous, glittering costumes and danced through the streets as if tomorrow would never come — and then, at cruel sunrise on Ash Wednesday, went back to being poor, black and bereft of prospects.

At least we won’t have to worry that this year’s Mardi Gras celebration will obscure New Orleans’ awful problems of race and poverty in a hailstorm of beaded necklaces and plastic doubloons. A lot of poor, black New Orleanians won’t be able to come to the party anyway because their homes are in ruins and they have had to make new lives for themselves in cities far away. Their absence is statement enough.

I don’t want to be too grouchy and judgmental about Mardi Gras, though. If carnival is what you do every year, then it’s also who you are. You probably don’t have a choice.

Fittingly, the first parades have taken place beneath leaden skies and been witnessed by sparse crowds.

The “krewes,” or social clubs, that organize the parades are having to scale back — fewer floats, shorter routes. Some of the parades would normally pass through neighborhoods that aren’t neighborhoods anymore and had to be shifted to the part of the city that still functions.

In any event, some good may come of this year’s attenuated Mardi Gras. One benefit is much-needed revenue: Only half the usual number of tourists may visit the city, but that’s better than nothing. It’s hard to imagine how the city will ever recover unless tourism can be revived.

The other benefit is our attention.

Hundreds of journalists from around the world have gone to New Orleans to cover Mardi Gras. Breathes there an editor who could resist this tailor-made “peg,” or opportunity, to revisit the picturesque disaster zone? Is there a reporter in creation nimble enough not to fall into the treacherous jazz-funeral analogy?

In the end, it doesn’t matter whether we see Mardi Gras as a triumph of the human spirit or a colossal waste of time. What really matters is that we see it at all — that we look at the ruined city and remember what happened there.

What matters is that we recall the promise President Bush made to rebuild New Orleans for all of its citizens and that we remind ourselves of the hundreds of thousands of people who still can’t go home.

What matters is that we think back to those Third World images of poverty and despair we saw during the flood and renew our pledge never to witness such scenes again.